UV light is an umbrella term for radiation whose wavelengths are in a range of 10˜400 nm in the electromagnetic spectrum, and it is invisible to the naked human eye. A UV light source having fluorescent effects, biological effects, photochemical effects, and the photoelectric effect, is a non-lighting electric light source mainly aiming at generating ultraviolet radiation, and is suitable for the fields of industry, agriculture, national defense, medical treatment, etc. UV light sources have fluorescent effects, biological effects, photochemical effects, the photoelectric effects, etc. of UV radiation, and are widely used in the fields of industry, agriculture, national defense, medical treatment, etc.
The use of UV light in fluorescent effects is mainly for fluorescence analysis. After absorbing UV light, a substance will emit fluorescence reflecting its characteristics. Qualitative and quantitative analysis of the substance can be carried out according to its fluorescence characteristics. Specifically, UV light can be used: (1) for an analysis of inorganic elements and organic substances; (2) for an analysis of oil layers, ore, medicine, food, and carcinogenic substances; (3) as an adjunct to the public security department for analysis of blood, drugs, etc., as well as for identification of authenticity of banknotes, documents, etc. in case investigation; (4) for flaw detection; (5) as a biomarker; and (6) as a military biosensor.
The uses of UV light in biological effects are mainly on: (1) UV light sterilization: UV light having the wavelengths in a range of 200˜275 nm has a sterilization effect which may be different according to different wavelengths thereof, wherein the sterilizing effect of the UV light having the wavelength in the range of 254˜257 nm is the best. UV light irradiation has a wide antiseptic function and can kill all kinds of microbes. The sterilization mechanism thereof is to make the microbial nucleic acids, protoplasmic proteins, and enzymes die in chemical changes after absorbing UV energy; (2) body-care: living in the irradiation of UV rays contained in sunlight can boost man's immunity. Irradiation of UV light having wavelengths in the range of 280˜400 nm can produce certain positive roles to human body organs, thus playing the role of keeping fit; (3) curing diseases: UV light may treat vulgaris plaque psoriasis skin diseases (such as psoriasis and vitiligo, etc.), internal diseases (such as chondropathy, infantile jaundice, etc.), surgical diseases (such as various cute inflammations), neurological diseases, and so on; study on treatment for late-stage malignant tumors by UV light autotransfusion, inactivate viruses, and so on; and (4) microbial mutation breeding and so on.
The use of UV light in photochemical effects: the energy gap that corresponds to UV light with wavelengths in the range of 200˜400 nm is in the range of 6.2˜3.1 eV, and the bond energy of chemical combination of many compounds is in the same range. Absorbing the energy may trigger lots of chemical reactions. Specific uses are as follows: (1) coating, pigment curing, photoengraving, printing down and duplication, photoetching and packaging of semiconductor devices, aging test of high polymer material, and the like; (2) organic photochemical reactions: under the UV light with the wavelengths in the range of 254˜400 nm, electrons in organic matters may jump from the ground state to the excited state to produce organic photochemical reactions that may result in decomposition of organic matters; and (3) UV light oxidation treatment of TNT (trinitrotoluene) waste water, and UV light combined with natural light photo catalytic treatment of UDMH (unsymmetrical dimethylhydrazine) waste water.
UV light also has important uses in the fields of agriculture and animal husbandry: (1) UV light having wavelengths in the range of 300˜400 nm is essential to plant growth; (2) insects are very sensitive to the UV light having wavelengths in the range of 300˜400 nm. which therefore can be used for trapping and killing pests in the farmland; (3) sterilizing to henhouses and pens with UV light, and irradiation to livestock may increase the growth rate of livestock and the laying rate, and reduce the mortality rate of livestock.
In addition, UV/near-UV light is also widely used in the fields of pumped dyes emitting, white light illumination, high capacity data storage, etc.
Thus, the UV light source has a broad prospect in use in the industrial and agricultural production and in daily life. Since the advent of the world's first high-pressure mercury lamp in 1935, the UV light source has begun to attract people's widespread attention. Before the 1950s, mercury lamps were the only artificial UV light sources, but failed to be applied in practice. With the advent of quartz glass, the maturity of the encapsulation technology, the development of the electric vacuum industrial, and the perfection of ultraviolet spectroscopy, the ultraviolet light source moved towards the truly valuable use stage. In addition to the earliest mercury lamps, some new types of UV light sources emerged one after another in the late 1950s, which can be divided into mercury arc lamps, metal halide lamps, electrodeless lamps, xenon lamps, excimer UV lamps, and UV light-emitting diodes according to the varieties of lamps. Among these UV light sources, the most commonly used at present is the gaseous UV light source which has the following problems: high toxicity of the host materials, secondary pollutions, inconvenient use of the devices, vulnerability, and the like.
In contrast, the emerging of Ultraviolet-Organic Light Emitting Diode (UV-OLED), which is environmentally friendly, of low cost, easy large-area production, easy integration with flexible substrates, and the like, can make up for the current inadequacy of UV light sources. Especially, the flexible OLED display device, which is not only soft and can be deformed, but also is not easy to damage, can be mounted at curved surfaces and even disposed on clothing. Thus it is becoming a research hotspot in the international display industry increasingly. Currently, there is no discovery of relevant reports about a flexible substrate based organic ultraviolet electroluminescent diode device.